Transcriptome analysis reveals the nutrient metabolism processes during the germination of Longzi black barley

Abstract Longzi black barley ( Hordeum vulgare L . var. nudum , LBB), a unique highland barley variety renowned for its superior nutritional profile, serves as an important crop in the Qinghai-Tibet Plateau. Despite its agronomic and nutritional importance, the molecular mechanisms underlying seed germination in LBB remain poorly understood. In this study, physiological changes and transcriptomic alterations during LBB germination were systematically investigated. Growth characteristics, nutrient contents, and gene expression profiles were monitored at multiple germination stages. A total of 22 923 genes were found to be expressed, and 11 188 differentially expressed genes (DEGs) were identified, with the greatest number observed at the mid-germination stage (36 h). Functional enrichment analysis was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. It was revealed that phytohormone signaling pathways were differentially regulated. Biosynthetic pathways related to starch and sucrose were consistently downregulated, while those involved in glutathione metabolism, phenylpropanoid biosynthesis, and flavonoid biosynthesis were significantly upregulated throughout germination. These results provide valuable insights into the transcriptional and metabolic changes during LBB germination, which may assist future studies on seed vigor and barley improvement.